There are a number of conventional processes for packaging integrated circuit (IC) dice. By way of example, many IC packages utilize a metallic leadframe that has been stamped or etched from a metal sheet to provide electrical interconnects to external devices. The die may be electrically connected to the lead frame by means of bonding wires, solder bumps that have been preformed on the active surface of the die, or other suitable electrical connections. In general, the die and portions of the leadframe are encapsulated with a molding material to protect the delicate electrical components on the active side of the die while leaving selected portions of the lead frame exposed to facilitate electrical connection to external devices.
In some applications, it is desirable to leave the back surface (opposite the active surface) of the die (or die attach pad if present) exposed; that is, not to encapsulate the back surface of the die with molding material. By way of example, it may be desirable to leave the back surface of the die exposed in order to increase heat dissipation out of the die. This is especially relevant for packages used in power applications. Additionally, in some applications it is desirable to solder or glue a heat sink to the die to help absorb and dissipate heat from the die. Increasing heat dissipation out of an IC die generally results in greater device performance and stability.
While existing arrangements and methods for packaging IC devices work well, there are continuing efforts to improve the thermal performance of IC devices.